The present invention relates to a semiconductor light-emitting device for transmission use (in particular, for IEEE 1394), display use and the like and a method for fabricating the device.
In recent years, semiconductor light-emitting devices are broadly used for optical communications and display panels. It is important for the semiconductor light-emitting devices for the above uses to have a high light emission efficiency, and it is further important for semiconductor devices for optical communications to have a high speed of response. Such devices have been actively developed lately.
The normal plane emission type LED's (light-emitting diodes) have an insufficient high-speed response, which is limited to about 100 Mbps to 200 Mbps. Accordingly, there is developed a semiconductor light-emitting device called the resonant-cavity type LED. This resonant-cavity type LED is a semiconductor light-emitting device that achieves a high-speed response and high efficiency by controlling the natural emission light with a light-emitting layer placed in a belly position of a standing wave generated by a resonator formed of two mirrors (Japanese Patent Publication No. HEI 10-2744503, U.S. Pat. No. 5,226,053).
In particular, POF (plastic optical fiber) has lately started being utilized for communications in a relatively short range, and there has been developed a resonant-cavity type LED having a light-emitting layer made of an AlGaInP based semiconductor material capable of emitting with high efficiency light at a wavelength of 650 nm around which the POF has a small loss (High Brightness Visible Resonant Cavity Light Emitting Diode: IEEE PHOTONICS TECHNOLOGY LETTERS Vol. 10, No. 12, DECEMBER 1998).
However, the aforementioned conventional resonant-cavity type LED has the problems as follows. In detail, the conventional resonant-cavity type LED has characteristics such that a resonant wavelength λ1 in the perpendicular direction and a resonant wavelength λ2 in a slanting direction have a magnitude relation of λ1>λ2 and a peak wavelength is varied depending on the angle of radiation from the LED chip. Normally, this radiation angle dependency is about 0.2 nm/deg to 0.3 nm/deg. This causes a problem that the color is varied depending on the angle of view when the LED chip is used for display.
When using the aforementioned LED chip for communications or as a light source for communications by means of, for example, a plastic fiber, an LED chip fabricated so as to have a peak at the wavelength of 650 nm at which the plastic fiber has a small loss in the perpendicular direction cannot be used in an optical system that utilizes the emission light in a slanting direction since the peak wavelength becomes shorter than 650 nm.